The disclosed subject matter relates generally to manufacturing and, more particularly, to a method and apparatus for reducing setups during test, mark, and pack operations.
There is a constant drive within the semiconductor industry to increase the quality, reliability and throughput of integrated circuit devices, e.g., microprocessors, memory devices, and the like. This drive is fueled by consumer demands for higher quality computers and electronic devices that operate more reliably. These demands have resulted in a continual improvement in the manufacture of semiconductor devices, e.g., transistors, as well as in the manufacture of integrated circuit devices incorporating such transistors. Additionally, reducing the defects in the manufacture of the components of a typical transistor also lowers the overall cost per transistor as well as the cost of integrated circuit devices incorporating such transistors.
Generally, a set of processing steps is performed on a wafer using a variety of processing tools, including photolithography steppers, etch tools, deposition tools, polishing tools, rapid thermal processing tools, implantation tools, etc. During the fabrication process various events may take place that affect the performance of the devices being fabricated. That is, variations in the fabrication process steps result in device performance variations. Factors, such as feature critical dimensions, doping levels, contact resistance, particle contamination, etc., all may potentially affect the end performance of the device.
After fabrication of the devices is complete, each wafer is subjected to preliminary functional tests, commonly referred to as final wafer electrical tests (FWET) that evaluate test structures on the wafer and SORT tests that evaluate each die. Wafers that pass these tests are then cut to singulate the individual die, which are then packed in substrates. Packed die are then subjected to additional tests against the specification of customers' orders to determine performance characteristics such as maximum operating speed, power, caches, etc.
Exemplary tests include initial class tests (ICL) that is a preliminary test for power and speed. ICL testing is usually followed by burn-in (BI) and post burn-in (PBI) tests that test packaged die under specified temperature and/or voltage stress, and automatic test equipment (ATE) tests that test die functionality. Then, packaged die with different characteristics go through system-level tests (SLT) in which they are tested against customer requirements on specific electrical characteristics. In SLT, packaged die are tested in an actual motherboard by running system-level tests (e.g., variance test programs). After completion of the testing, the devices are fused, marked, and packed to fill customer orders. This back-end processing is commonly referred to as the test, mark, pack (TMP) process.
TMP is the last process in semiconductor manufacturing before finished packages can be shipped to customers. The characteristics of the TMP process are high product mix and high volume. Even for the same product type, different variations may be present depending on specific customer requirements with respect to power, speed, etc. To satisfy these differing requirements, an extremely large number of processing specifications are used to define different temperatures, test programs, etc.
Due to the high product mix, the number of setup changes is large. While some setup changes are short (e.g., measured in seconds), other setup changes take 30 minutes or more (e.g., test program changes). Still other setup changes, such as smart burn-in setups, can require multiple shifts to complete. The large number of setup changes results in significant capacity loss. Hence, setup changes are a significant contributor to the utilization efficiency of the tools and to the overall throughput of the facility. This lost capacity reduces the efficiency, and thus, profitability of the facility.
Planning and scheduling techniques are difficult to implement for a TMP facility due to high uncertainties associated with both production and customer demand. For production lots in a TMP line, the future process flow is not readily determined as lots can be used to satisfy demands of different ordinary part numbers (OPNs). Depending on the requirements, some lots may be pushed to inventory and possibly even scrapped. Some lots change flows and specs as they pass through the TMP line. Due to these uncertainties associated with lots, it is not feasible to schedule devices in a TMP line using lot scheduling techniques.
This section of this document is intended to introduce various aspects of art that may be related to various aspects of the disclosed subject matter described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the disclosed subject matter. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art. The disclosed subject matter is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.